The present invention relates to abrasive cleaning apparatuses and, more particularly, to a mobile, abrasive cleaning device having means for recovering and recirculating the abrasive material.
The abrasive cleaning of surfaces may be accomplished by a number of methods, such as the use of portable grinders and blasting. The use of portable grinders is a slow and expensive operation, particularly for large surface areas, which also produces an environment of dust, rust, dirt, etc. In addition to presenting a potential health hazard to the personnel operating the grinders, the cloud of dust, rust, and dirt prevents the conduct of other operations or procedures in the area where the grinders are being used.
Blasting methods are more efficient than the use of portable grinders, but again, a potentially hazardous environment is presented by the cloud of abrasive material, rust, dirt, etc. In addition to these deficiencies that the blasting methods share with the use of portable grinders, another disadvantage results from the additional operation in which the spent abrasive material has to be recovered, separated from the foreign material and processed for reused, or be collected and discarded.
Devices are known which provide for controlling the dust environment created by operation of a blasting machine and also provide for recirculating the spent abrasive material. Examples of blasting machines which incorporate such devices are described in U.S. Pat. Nos. 3,977,128, 3,906,673, and 3,756,377. Each of these machines uses a power-driven, centrifugal blast wheel, into which a stream of abrasive material is axially fed, to be centrifugally expelled against a surface to be cleaned. The means for recovering and recycling the spent abrasive material include rotating brushes or pneumatic suction apparatuses. Normally, the area which is cleaned at any given time by these machines is generally rectangular in shape and is of limited dimensions. Therefore, considerable time is required to clean a sizable surface area. Additionally, some of these machines are heavy and bulky, and consequently are difficult to maneuver and require considerable manpower in their operation.
Another category of abrasive cleaning devices includes large stationary machines used to treat the surfaces of a material passed through the machines. In such machines, the abrasive material may be centrifugally directed against the material surfaces by a blast wheel, such as described in U.S. Pat. No. 3,517,465, or be downwardly directed by a fan-type impeller, such as described in U.S. Pat. Nos. 3,405,481 and 3,217,447. Examples of the devices provided in these machines for collecting, processing and recycling the spent abrasive material include pneumatic exhaust systems, endless bucket conveyor systems, or screw conveyors, with the latter two utilizing gravity to collect the spent abrasive material and a conveyor system to transport this material back into the abrasive feeding apparatus. These abrasive, surface treating machines, because of their stationary nature, are massive in size, and are not intended to be mobile nor designed to clean large, fixed surface areas.